Pteropods in Southern Ocean ecosystems

Hunt, Brian P. V.; Pakhomov, Evgeny A.; Hosie, Graham W.; Siegel, Volker; Ward, Peter; Bernard, Kim S.

doi:10.1016/j.pocean.2008.06.001

Cited by 211 publications

(231 citation statements)

References 86 publications

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“…DVM behaviour is also shown by other crustacean and non-crustacean zooplankton such as salps and pteropods (Nishikawa and Tsuda, 2001;Hunt et al, 2008), amphipods like Themisto gaudichaudi (Everson and Ward 1980), and copepods (Atkinson et al 1992) (Flores et al, 2011). Copepods also perform diel and seasonal vertical migrations, but are considered rather weak scatterers of sound (Stanton and Chu, 2000) at the frequency of 75 kHz used here.…”

Section: Species Performing Diel Vertical Migrationsmentioning

confidence: 98%

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Cisewski

Strass

2016

Progress in Oceanography

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The success of any efforts to determine the effects of climate change on marine ecosystems depends on understanding in the first instance the natural variations, which contemporarily occur on the interannual and shorter time scales. Here we present results on the environmental controls of zooplankton distribution patterns and behaviour in the eastern Weddell Sea, Southern Ocean. Zooplankton abundance and vertical migration are derived from the mean volume backscattering strength (MVBS) and the vertical velocity measured by moored acoustic Doppler current profilers (ADCPs), which were deployed simultaneously at 64°S, 66.5°S and 69°S along the Greenwich Meridian from February, 2005, until March, 2008 While these time series span a period of full three years they resolve hourly changes.A highly persistent behavioural pattern found at all three mooring locations is the synchronous diel vertical migration (DVM) of two distinct groups of zooplankton that migrate between a deep residence depth during daytime and a shallow depth during nighttime. The DVM was closely coupled to the astronomical daylight cycles. However, while the DVM was symmetric around local noon, the annual modulation of the DVM was clearly asymmetric around winter solstice or summer solstice, respectively, at all three mooring sites. DVM at our observation sites persisted throughout winter, even at the highest latitude exposed to the polar night. Since the magnitude as well as the relative rate of change of illumination is minimal at this time, we propose that the ultimate causes of DVM separated from the light-mediated proximal cue that coordinates it. In all three years, a marked change in the migration behaviour occurred in late spring (late October/early November), when DVM ceased. The complete suspension of DVM after early November is possibly caused by the combination of two factors: (1) increased availability of food in the surface mixed layer provided by the phytoplankton spring bloom, and (2) vanishing diurnal enhancement of the threat from visually oriented predators when the illumination is quasi-continuous during the polar and subpolar summer. 3Zooplankton abundance in the water column, estimated as the mean MVBS in the depth range 50 -300 m, was highest end of summer and lowest mid to end winter on the average annual cycle. However, zooplankton abundance varied several-fold between years and between locations. Based on satellite and in situ data of chlorophyll and sea ice as well as on hydrographic measurements, the interannual and spatial variations of zooplankton mean abundance can be explained by differences in the magnitude of the phytoplankton spring bloom, which develops during the seasonal sea ice retreat. Whereas the vernal ice melt appears necessary to stimulate the blooming of phytoplankton, it is not the determinator of the blooms magnitude, its areal extent and duration. A possible explanation for the limitation of the phytoplankton bloom in some years is top-down control. We hypothesize that the phytoplankton spring ...

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Section: Species Performing Diel Vertical Migrationsmentioning

confidence: 98%

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Cisewski

Strass

2016

Progress in Oceanography

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“…Proportional surface layer densities of Clio pyramidata, Thysanoessa macrura and Sagitta gazellae were close to zero during autumn and winter and Z1% of corresponding epipelagic densities in summer, indicating that they used the surface layer almost exclusively during the productive summer months. During summertime, shallow ice melt blooms are common while the pack-ice is breaking up, providing high concentrations of phytoplankton near the surface, a crucial food source for C. pyramidata and T. macrura (Pakhomov and Froneman, 2004;Hunt et al, 2008). Conversely, S. gazellae was probably attracted by copepods, euphausiid larvae and other grazers in surface waters Oresland, 1990).…”

Section: Significance Of the Surface Layer Habitatmentioning

confidence: 99%

“…Due to its high abundance and economic importance, Antarctic krill has received disproportionally high attention compared to other species. Besides Antarctic krill, however, the Southern Ocean hosts a unique and diverse pelagic fauna that by itself contributes substantially to the carbon and energy budgets of its ecosystems (Collins and Rodhouse, 2006;Hunt et al, 2008;Kruse et al, 2010a).…”

Section: Introductionmentioning

confidence: 99%

Seasonal changes in the vertical distribution and community structure of Antarctic macrozooplankton and micronekton

Flores

Hunt

Kruse

et al. 2014

Deep Sea Research Part I: Oceanographic Research Papers

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. b s t r a c tThe macrozooplankton and micronekton community of the Lazarev Sea (Southern Ocean) was investigated at 3 depth layers during austral summer, autumn and winter: (1) the surface layer (0-2 m); (2) the epipelagic layer (0-200 m); and (3) the deep layer (0-3000 m). Altogether, 132 species were identified. Species composition changed with depth from a euphausiid-dominated community in the surface layer, via a siphonophore-dominated community in the epipelagic layer, to a chaetognathdominated community in the deep layer. The surface layer community predominantly changed along gradients of surface water temperature and sea ice parameters, whereas the epipelagic community mainly changed along hydrographical gradients. Although representing only 1% of the depth range of the epipelagic layer, mean per-area macrofauna densities in the surface layer ranged at 8% of corresponding epipelagic densities in summer, 6% in autumn, and 24% in winter. Seasonal shifts of these proportional densities in abundant species indicated different strategies in the use of the surface layer, including both hibernal downward and hibernal upward shift in the vertical distribution, as well as year-round surface layer use by Antarctic krill. These findings imply that the surface layer, especially when it is ice-covered, is an important functional node of the pelagic ecosystem that has been underestimated by conventional depth-integrated sampling in the past. The exposure of this key habitat to climate-driven forces most likely adds to the known susceptibility of Antarctic pelagic ecosystems to temperature rise and changing sea ice conditions.

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“…Foraminifer assemblages are characterized by a southward dominance of polar species Neogloboquadrina pachyderma. In a review, Hunt et al, (2008) compiled pteropod abundance in the Southern Ocean and reported a switch from a dominance of Limacina retroversa australis north of the PF to Limacina helicina antarctica south of the PF.…”

Section: Introductionmentioning

confidence: 99%

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Rembauville

Meilland

Ziveri

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tWe report the contribution of planktic foraminifers and coccoliths to the particulate inorganic carbon (PIC) export fluxes collected over an annual cycle (October 2011/September 2012) on the central Kerguelen Plateau in the Antarctic Zone (AAZ) south of the Polar Front (PF). The seasonality of PIC flux was decoupled from surface chlorophyll a concentration and particulate organic carbon (POC) fluxes and was characterized by a late summer (February) maximum. This peak was concomitant with the highest satellite-derived sea surface PIC and corresponded to a Emiliania huxleyi coccoliths export event that accounted for 85% of the annual PIC export. The foraminifer contribution to the annual PIC flux was much lower (15%) and dominated by Turborotalita quinqueloba and Neogloboquadrina pachyderma. Foraminifer export fluxes were closely related to the surface chlorophyll a concentration, suggesting food availability as an important factor regulating the foraminifer's biomass. We compared size-normalized test weight (SNW) of the foraminifers with previously published SNW from the Crozet Islands using the same methodology and found no significant difference in SNW between sites for a given species. However, the SNW was significantly species-specific with a threefold increase from T. quinqueloba to Globigerina bulloides. The annual PIC:POC molar ratio of 0.07 was close to the mean ratio for the global ocean and lead to a low carbonate counter pump effect ( $ 5%) compared to a previous study north of the PF (6-32%). We suggest that lowers counter pump effect south of the PF despite similar productivity levels is due to a dominance of coccoliths in the PIC fluxes and a difference in the foraminifers species assemblage with a predominance of polar species with lower SNW.

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Pteropods in Southern Ocean ecosystems

Cited by 211 publications

References 86 publications

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Acoustic insights into the zooplankton dynamics of the eastern Weddell Sea

Seasonal changes in the vertical distribution and community structure of Antarctic macrozooplankton and micronekton

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

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